1. Field of the Invention
The present invention is directed to a system which generates a part program for a numerical control machine tool from a part definition drawing and more particularly to a system which plans the order of machining operations and produces the numerical control program code for the sequence of manufacturing operations which includes selecting the proper tools, feed speeds and machine tool.
2. Description of the Related Art
Conventionally when a new part such as a socket head for a nuclear reactor pressure vessel cap needs to be machined. A part designer will sit down at a CAD/CAM design work station and produce a drawing for the desired part. The drawing includes notations as to type of rough stock material and dimensions of the part. The drawing is given to a numerical control part programmer, a person who specializes in creating a numerical control part program from the drawing. The part programmer uses machine specifications to pick the particular machine to be used based on rough stock size, the physical characteristics of the machine, possible machining speeds as compared to the appropriate speeds for the material using the tools necessary for the different machining operations, the number of tools the machine will hold and whether the part must be manually turned around. The part program is then provided to a computer program called a code processor that generates the actual numerical control machine code for controlling the target machine. The program is then test executed by a machine tool and if bugs are discovered the part programmer revises the program.
In situations where a new part is encountered, the part programmer may spend several days to several weeks producing, debugging and testing the part program until a satisfactory program is produced. This process can sometimes be shortened if the part programmer has an extensive library of macro-programs that can be modified for different purposes. A macro-program is a program that is designed for a specific type machining operation and in which the various machining parameters, such as feeds and speeds, number of passes, length of each pass, etc. are left as variables to be set by a macrocall statement. A macro-program is very similar in function to a subroutine in other types of computer languages. Even when an extensive part program library including part macro-programs is available, the time between the initial part request and the finished product is very long. As can be seen from the above discussion, there is a need in the machine tool industry for a system which will generate part programs directly from drawings to speed up the process of producing the desired part and reduce the lead time necessary for manufacturing the part.